62. Geonoma tenuissima Moore (1982: 204). Type: ECUADOR. Los Rios: across Río Palenque from Centro Científico, 150–220 m, 22 March 1977, F. Essig 350 (holotype USF n.v.). Plants 2.4(1.5–3.0) m tall; stems 1.8(1.5–2.0) m tall, 0.8(0.6–1.0) cm in diameter, clustered, cane-like; internodes 1.6(0.8–2.8) cm long, yellowish and smooth. Leaves undivided, not plicate, bases of blades running diagonally into the rachis; sheaths 5.2(4.7–5.5) cm long; petioles 5.3(3.0–6.5) cm long, drying green or yellowish; rachis 27.0(22.0–34.0) cm long, 2.5(1.9–3.6) mm in diameter; veins not raised or slightly raised and triangular in cross-section adaxially; pinnae 1 per side of rachis; basal pinna length and width not applicable, forming an angle of 28(23–36)° with the rachis; apical pinna 13.5(11.5–15.8) cm long, width not applicable, forming an angle of 30(22–36)° with the rachis. Inflorescences branched 3–4 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, deciduous; prophylls 4.3(3.4–5.2) cm long, short, asymmetrically apiculate, the margins curved around the stem, the surfaces flat with dense, felty, brown tomentum, prophyll equal to and early deciduous with the peduncular bract, the surfaces not ridged, without unequally wide ridges; peduncular bracts 4.5 cm long, well-developed, inserted 0.2(0.1–0.3) cm above the prophyll; peduncles 3.1(1.6–4.7) cm long, 2.9(2.3–3.8) mm in diameter; rachillae 74, 6.8(3.5– 10.2) cm long, 0.6(0.4–0.8) mm in diameter, the surfaces without spiky, fibrous projections or ridges, drying brown, with faint to pronounced, short, transverse ridges, filiform with extended narrowed sections between the flower pits; flower pits alternately arranged (sometimes distorted by twisting and contracting of rachillae), glabrous internally; proximal lips without a central notch before anthesis, not recurved after anthesis, not hood-shaped; proximal and distal lips drying the same color as the rachillae, joined to form a raised cupule, the margins not overlapping; distal lips well-developed; staminate and pistillate petals not emergent, not valvate throughout; staminate flowers deciduous after anthesis; stamens 6; thecae diverging at anthesis, inserted almost directly onto the filament apices, the connectives bifid but scarcely developed; anthers short and curled over at anthesis; non-fertilized pistillate flowers deciduous after anthesis; staminodial tubes crenulate or shallowly lobed at the apex, those of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 5.3(4.6–6.0) mm long, 4.8(4.1–5.5) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, bumpy from the numerous, subepidermal, tangential, short fibers present, these coming to a point at fruit apices; locular epidermis without operculum, smooth, without pores. Distribution and habitat:— From 0°31’– 0°38’S and 79°08’– 79°18’W in western Ecuador (Montañas de Ila) at 597(520–700) m elevation in lowland rainforest (Fig. 40). Taxonomic notes:— Geonoma tenuissima is a member of the Geonoma lanata clade. It appears most similar to G. mooreana and G. scoparia. It differs from the former by its proximal and distal lips which are joined to form a raised cupule; and from the latter in its yellowish and smooth internodes. Subspecific variation:— No trait varies within species, nor is there any geographic discontinuity.

Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on pages 148-149, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362